Water heater thermostat



May 20, 1952 H. E. MALONE WATER HEATER THERMOSTAT Original Filed Dec. 14, 1948 INVENTOR. HOMER E. MAL ElNE.

BY Rn MAW ATTURNEYE Patented May 20, 1952 WATER, HEATER THERMOSTAT.

Homer E. Malone, Milwaukee, Wis., assignor to Perfex Corporation, Milwaukee, Wis., a corporation of Wisconsin Original application December 14, 1948, Serial No.

1950, Serial No. 159,881

3 Claims.

This invention relates generally to switching apparatus and more particularly to thermostatic switching apparatus for the control of the application of heat to domestic hot water storage tanks.

An object of this invention is to provide a thermostatic switching apparatus in which the switch contacts and accompanying parts are separated by a casing wall from the thermal responsive actuator and from the heat to which the actuator responds.

A further object of this invention is to provide a thermostatic switching apparatus for a domestic hot water storage tank in which the thermal responsive switch actuator respondsprincipally to heat radiated from a wall of the storage tank.

Other objects and attendant advantages will be appreciated by those skilled in this art as the invention becomes better understood by reference to the following description when considered in connection with the accompanying drawings in which:

Fig. 1 represents a rear view of a portion of the thermostatic switching apparatus including the temperature responsive element and the casing.

Fig. 2 represents a sectional view of the thermostatic switching mechanism taken generally along the line IIII of Fig. 3.

Fig. 3 is a perspective view of the switching apparatus installed on a hot water storage tank.

Referring to Figures 1, 2 and 3, there is shown rectangular casing I having extending portions II and I2 which are utilized in mounting the casing on a suitable mounting bracket l3 (Figure 3). Bracket I3 is secured by any suitable means, such as welding to a hot water storage tank l4.

Pivotally mounted within casing 10 is a support member IS, the pivotal mounting being accomplished by means of the tabs 11 and [8 extending loosely through rectangular openings in the side of easing ID. A thermal responsive switch actuator 19, consisting of a bimetal strip is secured by any suitable means such as rivets, to the end of member 16 adjacent the pivotal mounting tabs l1 and I8. Strip l9 has its free end notched, as at.'2 I, for engagement with a connecting means or link 22 formed of insulating material, which transmits.v motion of strip I9 to the switching mechanism as will presently be explained.

A three sided housing 23 is mountedatop the casing 10 and secured theretoby any suitable means such as screws 24 (Figure 3) and downwardly extending tab (Figure 2). An adjusting Divided and this application May 4.

post 21 extends through an opening in the top of housing 23 and through an opening in casing I0. Post 21 is held against longitudinal displacement by means of a bracket 28, channel shaped in cross-section, having a first arm or flange 29 and a second arm or flange 30, arms 29 and 30 each having openings therein through which post 21 extends. Splines on post 21 are forced into the opening in arm 29, thus rigidly securing post '21 to bracket 28. It will be noted that the central web portion of bracket 28 does not extend to the top of the housing 23 (Figure 2), thus serving to permit insertion of a spring washer 33 between the top of housing 23 and the arm 29 which resiliently urges post 21 to its extreme downward position as determined by arm 30 of bracket 28. Bracket 28 bears against an antifriction washer 34, inserted between arm 30 and casing I0.

Post 21 extends freely through an opening in member 16, thereby serving as a lateral support but permitting limited longitudinal movement of the free end of member [6. The free end of member I6 is formed so as to provide an arcuate cam track 36 having a high point '31 and a low point 38. A tension spring 40 is secured between a point of attachment on the side Wall of housing 23 and an extension 39 of the member l6. Casing I0 has a cut out portion 3| adjacent the cam track 36 and extension 39, as may best be seen in Figure 1, permitting spring 4|] and adjacent parts to extend freely between the interior of housing and the interior of easing ill. The purpose of spring 40 is to bias member l6 upwardly against a cam follower 4| which is threaded through an opening in arm 30 and extends downwardly to abut cam track 36. The arm 29 has an upturned portion 42 which extends through an arcuate slot 43 (Figure 3) in the top of housing '23 and in conjunction with suitable scale markings which may be inscribed adjacent slot 43 serves to indicate the rotational position of post 21, and consequently cam follower 4 I, with reference to cam track 36.

From Figure 2 it will thus be seen that counterclockwise rotation of post 21 will move cam follower 4| to the high point on cam track 36. Since post 21 cannot move longitudinally, member 16 and consequently bimetal 19 will be moved to'its lowermost reference position. Conversely, clockwise rotation of post 21 places cam follower 4| in the low point on cam track 36 and establishes the high reference position for bimetal l9. Adjustment of post 21 thus fixes the control point of the apparatus by establishing the reference position of strip [9 from which temperature change may cause further movement of strip 19 in either direction depending on the direction of the temperature change.

Referring now to Figure 2, it will be seen that the switching apparatus, operated by bimetal IS in response to temperature change, is enclosed in a box-like case formed of Bakelite or other similar insulating material and has an upper half comprising switch plate or base 45 and a lower half comprising switch plate 46. This Bakelite switch casing is mounted adjacent the housing 23 and is secured in place by means of screws 32 (Figure 1) which extend through casing 10, through switch plate 46 and are threaded into tapped holes (not shown) in the switch plate 45.

Upon reference to Fig. 2, it will be noted that the stationary parts of the switching apparatus are mounted on the switch plate or base 45. The switching apparatus as illustrated in Fig. 2, forms no part of the present invention but is claimed in my co-pending application Serial No. 65,233, filed December 14, 1950. This structure is of the bridging contact, double throw type, having two pairs of movable contacts (only one contact of each pair, I03 and I08, being shown) and two pairs of fixed contacts (only one contact of each pair, 41 and 50, being shown). The fixed contacts are electrically connected to the external terminals (Fig. 3) 5T, 58, 59, and 6G by lugs, one of which is shown at 54. Adjustably secured to base are two downwardly depending tabs, only one of which, 14, is shown. Pivotally mounted on the tabs, by means of pin 15, is a contact carrying lever 83, having a central portion 84 and ears only one of which, 86, is shown. Pin 6 extends loosely through the ears 14 and 8G and their adjacent counterparts (not shown) thereby forming a central pivotal, mounting for the lever 83. Notched bosses (one of which is shown at 11) permit the pin it to be adjustably moved in a vertical plane. Oilset brackets 93 and 94 are connected to each end of the lever 83 forming a carrying means for the movable contact assemblies and armature portions, E09, cooperating with small permanent magnets H and 12 mounted on the base 45.

From the foregoing it will be apparent that lever 83 and its associated contacts form the movable portion of a double throw, bridging contact structure, and that, as viewed in Figure 2, a downward movement of link 22 will pivot lever 83 about pin 16 in a direction to bridge the electrical gap between contacts and its adjacent counterpart with a snap motion and will open an electrical gap between contacts 4! and its adjacent counterpart. An upward movement of link 22 will, conversely, move the parts to the position shown in Figure 2, i. e., with contacts 50 open and contacts 4'! closed.

In operation, referring to Figures 2 and 3, the assembled mechanism may be mounted on a hot water storage tank M by means of bracket 13. Bracket 13 has a cut out portion of the same general configuration as the open face of casing [0 so that the bimetal strip [9 is exposed to heat radiating from the tank l4. As shown in Figure 2, the post 27 is set in some intermediate position, for example, a position corresponding to a control point of 150 F. Strip I9 is in its cold position indicating the water in tank 14 is at a temperature lower than the control point setting of 150 F. Under these conditions the contacts and their adjacent counterparts |034l connected to terminal screws 51 and 58 are closed and the contacts and their adjacent counterparts l0850 connected to terminals 59 and 60 are open. These terminals may be connected to suitable apparatus (not shown) for changing the temperature of the contents of tank I4. Should the temperature of the contents of tank l4 increase to a value greater than F., the control point setting, the additional heat radiated from the sidewall of tank 14 to the bimetal strip l9 will caus it to move downwardly (as viewed in Figure 2) to open contacts 103-41 and close contacts IOB50.

It will be apparent that the features of the present invention, including the separation of the switching mechanism and the temperature responsive element into separate housings to remove the switching mechanism from the directly heated area, are equally applicable to double throw and single throw switch mechanisms and that the construction provides for a maximum of interchangeable parts between these two modifications.

Various modifications coming within the spirit of the invention may suggest themselves to those skilled in the art and hence the invention is not to be limited to the specific form shown, except to the extent indicated in the appended claims.

What is claimed is:

1. A thermostatic switching apparatus for controlling an electric circuit comprising: a casing, switching mechanism secured to the outside of said casing, an opening in said casing, a bracket mounted on said casing in overlying relation to said opening, an arcuate slot in said bracket, scale markings on said bracket adjacent said slot, an elongated movable member pivotally mounted within said casing, a bimetal element secured to said movable member and linked to c said switching mechanism, an arcuate cam track supported by said movable member, an adjusting post extending loosely through said bracket, said casing and said movable member, a first arm comprising a temperature indicator rigidly secured to said post adjacent said bracket and having a portion adapted to move in said arcuate slot in said bracket upon rotation of said post and to cooperate with said scale markings to indicate the rotative position of said post, a second arm rigidly secured to said post adjacent said casing and carrying a cam follower adapted to move over said cam track upon rotation of said post whereby rotation of said post results in pivoted movement of said movable member within said casing.

2. A thermostatic switching apparatus for controlling the application of heat to a hot water storage tank and reacting to the heat radiated from a wall of said tank comprising: a casing, switching mechanism secured to the outside of said casing, an opening in said casing, a bracket mounted on said casing in overlying relation to said opening, an arcuate slot in said bracket, scale markings on said bracket adjacent said slot, an elongated movable member pivotally mounted within said casing, a bimetal element secured to said movable member and linked to said switching mechanism, an arcuate cam track supported by said movable member, an adjusting post extending loosely through said bracket, said casing and said movable member, a first arm comprising a temperature indicator rigidly secured to said post adjacent said bracket and having a portion adapted to move in said arcuate slot in said bracket upon rotation of said post and to cooperate with said scale markings to indicate the rotative position of said post, a second arm rigidly secured to said post adjacent said casing and carrying a cam follower adapted to move over said cam track upon rotation of said post whereby rotation of said post results in pivotal movement of said movable member within said casing.

3. A thermostatic switching apparatus for controlling an electric circuit comprising: a casing, switching mechanism secured to the outside of said casing, an opening in said casing, a bracket mounted on said casing in overlying relation to said opening, arcuately placed scale markings on said bracket, an elongated moveable member pivotally mounted Within said casing, a bimetal element secured to said moveable member and linked to said switching mechanism, an arcuate cam track supported by said moveable member, an adjusting post extending loosely through said bracket, said casing and said moveable member, a first arm comprising a temperature indicator REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,989,277 Jefi'rey Jan. 29, 1935 20 2,044,397 Persons June 16, 1936 2,269,863 Shaw Jan. 13, 1942 

